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We have developed chemical-based methods to produce binary assemblies of nanocrystals. The ordered arrays that result are superlattices that mimic the structures of known crystal phases. Applications of this new type of material extends into the realm of optical science and technology. The model is of single component nanocrystals in the 5-20 nm range, which build multicomponent structures of micrometer dimensions. The method presents the opportunity to choose from a variety of inorganic nanocrystals (e.g. semiconducting, magnetic) in order to prepare superlattices with uniquely tunable properties. Transition metal and transition metal oxide nanocrystals are nanometer dimension crystals composed of one or more metals from the d block of the periodic table, and oxygen. The nanocrystals have capping groups which render them discrete, stable, and enable them to be manipulated in a variety of media such as solvents or polymers. The nanocrystals are ideally monodisperse, uniform in composition, crystalline, and can be prepared over a range of sizes from 5-20 nm. The selection of composition for the nanocrystals is based on materials with known interesting properties (optical, electronic or electrical) in the bulk phase. Once fully characterized, the nanocrystals can be considered as components for the assembly of a nanostructured composite material designed to exhibit interesting collective properties with tunable control at the nanoscale.
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